services.AddSingleton<CitiesFrameworkCore.RabbitMq.RabbitMQConsumer>();

public void ProcessMessages()
    {
        using (_connection = _factory.CreateConnection())
        {
            using (var channel = _connection.CreateModel())
            {
                Console.WriteLine("Listening for Topic <cities.createCity>");
                Console.WriteLine("-----------------------------------------");
                Console.WriteLine();

                channel.ExchangeDeclare(ExchangeName, "topic");
                channel.QueueDeclare(CitiesTopicQueName, true, false, false, null);

                channel.QueueBind(CitiesTopicQueName, ExchangeName,
                    "cities.createCity");

                var consumer = new AsyncEventingBasicConsumer(channel);
                consumer.Received += Consumer_Received;
                channel.BasicConsume(CitiesTopicQueName, true, consumer);
            }
        }


rabbitConsumer.CreateConnection();
rabbitConsumer.ProcessMessages();

var sender = new RabbitMQClient();
var obj = new CityDto();
sender.SendCity(obj);

public class RabbitMQClient
{
    private static ConnectionFactory _factory;
    private static IConnection _connection;
    private static IModel _model;

    private const string ExchangeName = "Topic_Exchange";
    private const string CitiesTopicQueName = "CitiesTopicTopic_Queue";
    //private const string PurchaseOrderQueueName = "PurchaseOrderTopic_Queue";
    private const string AllQueueName = "AllTopic_Queue";

    public RabbitMQClient()
    {
        CreateConnection();
    }

    private static void CreateConnection()
    {
        _factory = new ConnectionFactory
        {
            HostName = "localhost",
            UserName = "guest",
            Password = "guest"
        };

        _connection = _factory.CreateConnection();
        _model = _connection.CreateModel();
        _model.ExchangeDeclare(ExchangeName, "topic");

        _model.QueueDeclare(CitiesTopicQueName, true, false, false, null);
        _model.QueueDeclare(AllQueueName, true, false, false, null);

        _model.QueueBind(CitiesTopicQueName, ExchangeName, "cities.createCity");

        _model.QueueBind(AllQueueName, ExchangeName, "cities.*");
    }

    public void Close()
    {
        _connection.Close();
    }

    public void SendCity(CityDto city)
    {
        SendMessage(city.Serialize(), "cities.createCity");
        Console.WriteLine("Message SendCity Last Line");
    }

    public void SendMessage(byte[] message, string routingKey)
    {
        _model.BasicPublish(ExchangeName, routingKey, null, message);
    }
}